The Pettman general service fuze, used in England, is a percussion fuze of unusual form, equally applicable to spherical or oblong projectiles. It consists, essentially, of a hollow screw-plug containing a ball covered with detonating composition, which is freed from its bearings by the shock of discharge, and explodes the shell upon impact by striking the walls surrounding it. The detonating ball sometimes fails in breech-loading guns, the motion of the projectiles being too steady to shake it out of its seat. For this reason a plain ball, as it is called, is placed in the upper part of the fuze, and held between two disks. These separate upon discharge, and the ball is thrown outwards by the rotation opposite an annular groove in the lower plug or disk filled with fulminate, which is exploded upon impact, the lower plug being driven against the ball by its inertia. This fuze is, properly, a concussion-percussion fuze.
Fyroz, or Feroze (written also Ferose, Firoz, Firouz, Feyrouz, and Firuz). A Persian word signifying “victorious,” and forming the name of several ruling kings in Persia and Hindostan.
G.
Gabion. A kind of basket made of osier twigs, of a cylindrical form, having different dimensions, according to the purpose for which it is used. Filled with earth, these gabions serve in sieges to carry on the approaches under cover, when the assailants come near the fortification. Batteries are often made of gabions, which likewise serve for revetments in constructing parapets of loose earth.
Gabionage. Gabions when used for fortification.
Gabionnade. A work hastily thrown up; especially, one formed chiefly of gabions. A parapet en gabionnade is a parapet constructed of gabions.
Gabions, Corrugated Iron. Are gabions made of corrugated iron. For this purpose, the corrugated sheet should be 6 feet long, 33 inches wide, and of iron weighing three-quarters of a pound to the square foot.
The corrugations running transversely, the sheet is easily bent into a cylindrical form, in which it is retained by two clamps, the holes for which are punched near the corners of the sheet. The chief advantage claimed for the corrugated over the hoop gabion is, the readiness with which it can be put together in the field. It is also rather more portable, and stakes are dispensed with; but it is inferior to the hoop gabion in stiffness.
Gad. The point of a spear, or an arrowhead; a steel spike on the knuckle of a gauntlet.